Well I ended up buying seasons 4, 5 and 7. It makes sense to buy all of them I agree but I'd rather watch these then see if I want to buy the rest. Thank you for all your informed opinions 
I think I haven't explained myself very well about why I think seven's inclusion is sexist. I want to clarify first by saying I think she's is an attractive woman, great body symmetrical face etc. My husband thinks she's a "prawn" (some of you may have to google that). So she's not to everyone's taste iykwim. But I say she is extrememly beautiful and i'd say 99.9% of straight men would find her extremely hot.
I also think she's a pretty good actor, though I don't know how hard it is to act robotic/ angry I feel she does a good job of it. So nothing personal against Jeri Ryan's acting, she's one of the best on the show imo.
What got me (and remember I'm a new fan so I haven't seen all of the series) is the fact she's wearing a skin tight lycra suit which leaves nothing to the imagination when the rest of the crew are wearing star fleet uniforms. Why? I mean if they are going to sex it up with seven's character,they could have at least have had some studly guy walking around shirtless for 4 seasons for us ladies couldn't they?
It all seems a bit obvious to me, but if someone can offer me a good and I mean GOOD reason not some bull shit sci fi fantasy reason as to why she has to wear that suit then I will stand corrected.

I think I haven't explained myself very well about why I think seven's inclusion is sexist. I want to clarify first by saying I think she's is an attractive woman, great body symmetrical face etc. My husband thinks she's a "prawn" (some of you may have to google that). So she's not to everyone's taste iykwim. But I say she is extrememly beautiful and i'd say 99.9% of straight men would find her extremely hot.
I also think she's a pretty good actor, though I don't know how hard it is to act robotic/ angry I feel she does a good job of it. So nothing personal against Jeri Ryan's acting, she's one of the best on the show imo.
What got me (and remember I'm a new fan so I haven't seen all of the series) is the fact she's wearing a skin tight lycra suit which leaves nothing to the imagination when the rest of the crew are wearing star fleet uniforms. Why? I mean if they are going to sex it up with seven's character,they could have at least have had some studly guy walking around shirtless for 4 seasons for us ladies couldn't they?
It all seems a bit obvious to me, but if someone can offer me a good and I mean GOOD reason not some bull shit sci fi fantasy reason as to why she has to wear that suit then I will stand corrected.