Which game to start with?

Alright - you got me. I'm back. I'm going to pick up Pokemon for the first time since red and blue.

Where to start on the 3DS?

Is choosing your first Pokemon still as hard as it used to be? WHAT IF I CHOOSE THE WRONG ONE!? o_O

Thanks in advance!
HmR

I think Pokémon X or Y is a very nice choice for you. It may turn out nostalgic! Choosing pokémon can still be hard, but I have a clear favourite :)

I'd also pick X or Y if I were you. They added quite some stuff for the old fans.

Picking your starter is still hard, but because breeding was added in Gold and Silver and wifi tradig in Pearl and Diamond, getting the other starters isn't as hard as it was back in the days or Red and Blue.

Platinum or HeartGold/Soul Silver, I say. Largely because the slower speed (The general movement of literally everything) is slower and harder to get into after the fact. Plus they're pretty solid entries, so I would recommend them regardless.

But if you mean titles specifically for the 3DS, ORAS, certainly. The games reliance on HMs is VERY noticeable after XY. Even having loved Emerald as a kid, it did bother me after the time I spent with XY.

I start with Emerald and choose Mudkip by mistake and later when it evolved into Swampert and it was very powerful and cool so my favorite Pokemon is Swampert

Man there's a lot to chose from - its crazy how much it can change over time. I think X and Y may be the go - thanks for all your help!

Best to start from X & Y it explains a lot about mega evolution. but you can skip that and play the remake of RSE because XY gym leaders and elite four just being easy peasy

I say either Pokemon HeartGold&SoulSilver or XY, because they have peeks of Kanto I think you'll enjoy :)
But after those two play Platinum and Omega Ruby & Alpha Sapphire! :)

Then Sun & Moon! :D

My girlfriend got me a 3DS of Christmas as well as Y. It was fucking awesome, and I would highly recommend playing X or Y before ORAS.

I'd suggest either Black, White, B2, or W2. Black and White are basically series reboots, and B2 and W2 are in my opinion the closest to perfect Pokemon games that are out there. All, however, are fantastic games that are fun, feature-rich, and feature a good amount of difficulty without being too grindy. 6th gen is ridiculously easy and kind of shallow, so I'd recommend you play those later.