CSI Miami cast.

Who would replace him?

Speedle (dead)
Cardozo (dead)
Stetler (pokey)
Donner (retired)
Valera (retired)

As you can see, there isn't much to go on here. It's become clear that there is a budget for this show, and bringing in a new character is probably not going to happen (paging Eddie Cibrian...). And all the older characters you might have liked...well most of them have been killed off.

Characters have traits. So Ryan cocks his head when he looks at you, big deal. He's been written into the show as the whipping boy, and he takes it and gives some of it back. I guess you could call him scrappy.
As said above, everyone has characters they like and dislike and we are all different. For me, personally, Ryan is the best character in the show. Yes he isnt perfect, but that makes him more realistic.
Im not always pleased with the way the character is written, but there is no way he is 'dumb' or 'useless.' He has shown in countless episodes that he is very intelligent, and has broken the case in quite a few of them.
I actually like the head tilting, and the arms folded on Ryan- its cute. We all have our little quirks!

hell yeah, Solitaire, 1000000 % agree with you.
Ryan was, is and will be my favorite character and i will love him just the way he is.

it doesn't matter whether he's flawed, arrogant or just tilting his head and crossing arms. heck with that those who knows what i'm talking about will understand me ( i hope so ).
ahh if i like him there's appearant reason for that.

as for other certain characters, meh i'm concentration only on those i like, the rest stays behind. won't judge anyone.
Sorry to butt in; but I think most of them are flawed. Eric is pouty, angry and judgemental, Calleigh is self-righteous; so what if Ryan tends to be a little arrogant at times, he has a more forgiving nature and Natalia she's just plain sweet. We're not all going to agree on our favorite character; but for all their short-comings I think this has been the year they are finally pulling it together and working well as a team. I am finally enjoying each character.

Very nicely stated, slower. They are ALL flawed and have their annoying traits (Horatio is annoying the heck out of me lately). It's what storylines and drama are based on.

The exciting part for me is after all this time we are FINALLY getting a chance to SEE Ryan and Natalia traits. That in and of itself is a step in the right direction. I personally don't find either one of them annoying. I find them both a breath of fresh air.

Personally, I could do without Calleigh. On the bright side (for just me) her reduced appearances have made this season a real treat for me. :)

I know that the latter part of the season and into next season (if the show survives) my "treat" will be ending. That's okay. They have improved immensely with regard to working as a team this season. Hopefully when Calleigh returns full-time the teamwork won't fall by the wayside.