Depends on the game and which character just appeals to me for whatever reason. For instance when the first Tekken rolled into our arcades way back when I chose Paul right away, just because it was the first time a fighting game character had my name, and I've stuck with him in every iteration of any game he's been in. I also chose Wang for the sole purpose it was fun to say I beat people with my Wang. (juvenile, but hey... it was the reasoning at the time). Also in my much younger competitive arcade days besides my "main" I ALWAYS took the character that people considered the crappiest in the game, and made a point of learning them to prove they could be viable, and usually succeeded somewhat. But these days I'm too old to do that crap lol. Ahh to have the reflexes of a 20-year old again.
I also tend to lean towards grappler/charge characters, but mainly I happen to like certain character's designs and the way they look and they coincidentally fall into those two categories. Dedicated T.hawk and Vega player since their first SF incarnations. Was a Sodom player in Alpha series. Also a Bella main in SG and it's honestly my favorite game overall just because it appeals to me so much visually (and musically as well). Just recently started playing GG a lot and May immediately stood out to me because she was a lil' pirate chick who fought with a huge freakin' anchor which I thought was pretty cool. Again coincidentally she has charge moves and a command throw :D. But then again I play Yosuke in P4a who is a total rushdown character again just because I liked his design and the fact he always has headphones on (which I also tend to do.) Kilik in Soul Calibur since day one strictly because I'm a huge fan of Jet Li's older movies in which he fights amazingly well with a staff in the majority of them. Joker and Harley in Injustice just because they've always been my favorite DC characters. Shun in VF series also because Jackie Chan's Drunken Master was one of my most-watched martial arts films when I was younger. My 2nd in SG is Peacock, a zoner, just because I adore all the old cartoon references she contains.
So basically, it all pans down to which character I like. Not whatever "tier" they fall into or just because they fall into one archetype. Honestly if there's no character I like visually or design-wise, I usually lose interest in the game entirely (like D.O.A for example. Whoopeee it has bewbs. But no character in that game ever really "hooked" me design-wise). Even if they are considered super low tier or craptastic I still have fun playing those specific characters whether I win or lose, and after 20+ years of fighting games, you realize that's what matters most.