sorry if this seems a really stupid question.
i was wondering if it really matters where i sit at a poker table. is it better to sit at seat 1, 10 or smack bang in the middle at seat 5?

or is just down to a persons choice.

thanks

the actual seat you are sat in makes no difference, it is simply a persons choice.

however, positioning is very important and is quite a different subject. it relates to where you are in relation to the blind.
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for the most part, you want loose aggressive players to the right of you, and tight passive players to the left. this does two things:
1) allows you to see how the aggressive player is going to play before you invest money.
2) gives an opportunity to dictate how the tight passive player is going to play his hand.
like rino said it depends on your style, but those two things you should want in your game no matter what your style is. the only real benefit to playing this position opposit (loose to the left tight to the right) is that you can try to push the tight player out of a hand, and you can slow play the aggressive behind you. but those are only circumstantial instances. for the most part you''ll want to adhere to the reasons in 1) and 2).
for online play the physical table seat is irrelevant, in a casino i generally choose to be in the middle because i can see everyone and the flop easily.