Good Feat for a Human Artificer?

[Anderlith]

Looking for a good feat for a Thunder Cannon toting Artificer. What's a good one?

[SharkForce]

well, sharpshooter will straight-up make you better at shooting stuff. you almost certainly don't want to use the power attack part, but the other parts are more than good enough anyways; you ignore anything less than full cover, and you can shoot to your maximum range (of 500 feet) with no penalty instead of only 150 feet. that's pretty substantial.

apart from that, most of the generically good feats: healer, inspired leader, lucky, ritual caster, magic initiate, etc.

if you're going to be the primary person responsible for finding traps, dungeon delver may be good. maybe mounted combatant (it won't help you attack, at least, not with ranged weapons, but it can help you keep your companion alive, which can be nice).

or just pick something you think will fit.

[Anderlith]

I was thinking of going with either dungeon delver or ritual caster, so i can have a familiar, any other useful rituals?

[NecroDancer]

Ritual Caster is a good choice. Tenser's Disk and Unseen Servant are also good choices.

[EvilAnagram]

Can't go wrong with Linguist.

[Anderlith]

Ritual Caster is a good choice. Tenser's Disk and Unseen Servant are also good choices.

Is there any real difference between Magic Initiate & Ritual Caster?

[SharkForce]

Is there any real difference between Magic Initiate & Ritual Caster?

a rather large one. magic initiate gives you cantrips, which ritual caster never can, amd gives you a single use of a single spell from a spell list (and knowledge of that spell, if you have slots and the ability to use spells known from that class). it also makes you count as a spellcaster, so that you can attune to magic items that require spellcasters or take feats that require being a spellcaster. if the spell is a ritual, you don't have any ability to cast it as one.

ritual caster gives you a couple of ritual spells only, not any spell from the appropriate list, and allows you to learn more ritual spells if you can gain access to them somehow. you need to keep a book, and you can cast any spell from that book as long as you have it... but only as a ritual. it gives you no knowledge of the spell in any other form.

over the long term, ritual caster (probably choose wizard class) can give you a wide selection of rituals like alarm or detect magic. magic initiate gives you a bit of useful spellcasting.

[ImproperJustice]

It is worth noting that the artificer can cast detect magic and identity as rituals.

I think what you choose will largely be based on the role you may fill in the party.

I'm currently running a 5th level Alchemist in a party with a Barbarian (re flavored as a Samurai), a Battlemaster, and a Devotion Paladin.

In our last fight against an Adult Black Dragon I took on the main role of emergency healer with the healer feat. It's pretty handy. Just cast Sanctuary on yourself and go to work.

The others have given some good suggestions.
Will you be the Ranged specialist, healer, or trap springer?

Mounted Combat can be solid for when you get your servant, and Medium Armor Master could fit certain Artificer builds if you snipe/trap spring.

[Geeknamese]

Magic Initiate and grab two cantrips and a spell so that you can do something other than shoot a gun. My advice after playing the Artificer for some time, grab Shocking Grasp for one of the cantrips to help you get away from melee and back into sniper range. For the 1st level spell, (talk your DM into letting it be a clockwork construct like the Familiar in the Kaladesh UA) Find Familiar is an amazing spell to give you some extra utility when you're not firing your gun and suffering from your limited 1/3 casting.

Sometime down the road, you may want to pick up Sharpshooter for the thematics and to be able to fire from super long range without having to worry about cover. The Sharpshooter damage is nice and you could have a familiar to offset the penalty but you're only getting one shot per round so that +10 isn't all that great.

[Anderlith]

It is worth noting that the artificer can cast detect magic and identity as rituals.

I think what you choose will largely be based on the role you may fill in the party.

I'm currently running a 5th level Alchemist in a party with a Barbarian (re flavored as a Samurai), a Battlemaster, and a Devotion Paladin.

In our last fight against an Adult Black Dragon I took on the main role of emergency healer with the healer feat. It's pretty handy. Just cast Sanctuary on yourself and go to work.

The others have given some good suggestions.
Will you be the Ranged specialist, healer, or trap springer?

Mounted Combat can be solid for when you get your servant, and Medium Armor Master could fit certain Artificer builds if you snipe/trap spring.

My role will be part time caster, part time trap springer. We dont have a wizard, we have a land druid & a cleric (he might choose nature) & me. I expect to fill the knowledge & utility role of a wizard, with a bit of trap disarming & dungeon savy. I'm a gunslinger artificer with it fluffed as a magitek blasting staff. I want to be able to take care of all the contingencies that i can & be prepared for anything. I'm expecting to buy the most equipment & put it to good use. While my gunslinging will carry me damage-wise in combat, i dont want to take Magic Initiate for attack cantrips, Im really determined to have a familiar. I think i may go with ritual caster solely for the utility it will bring.

Once i get the mechanical sidekick, i plan on fluffing a giant owl or giant eagle as a magitek dragon & flying all the time at range, shooting.

[ImproperJustice]

My role will be part time caster, part time trap springer. We dont have a wizard, we have a land druid & a cleric (he might choose nature) & me. I expect to fill the knowledge & utility role of a wizard, with a bit of trap disarming & dungeon savy. I'm a gunslinger artificer with it fluffed as a magitek blasting staff. I want to be able to take care of all the contingencies that i can & be prepared for anything. I'm expecting to buy the most equipment & put it to good use. While my gunslinging will carry me damage-wise in combat, i dont want to take Magic Initiate for attack cantrips, Im really determined to have a familiar. I think i may go with ritual caster solely for the utility it will bring.

Once i get the mechanical sidekick, i plan on fluffing a giant owl or giant eagle as a magitek dragon & flying all the time at range, shooting.

Sounds like a good Artificer time to me!