Some good expensive breeders are green house, serious seeds, mr. nice, Dutch passion, DJ shorts seeds, and chimera are top notch. I'd recommend sensi, but they make white label seeds and those I know do suck so just because of that I couldn't recommend them (everything a company makes should always be top notch otherwise you lose my trust).
For good cheap seeds (don't let these prices fool you they make good shit) I'd say I'd only go with Nirvana. A lot of their seeds are F2 or are crossed with a sunk variety, but they still make some great shit and it's a great value, personally I could care less if a seed is a F2 gen or a cross some people do so that's why I mention it. I'd still recommend them because everything I've ever read about them has been positive. Hell at least they don't charge you an arm and a leg and imagine behind closed doors all breeders sell you F2 seeds or some crossing with other strains.
For strains I say first grow the classics for your first grow since they are a must (white widow, blue berry (kind of a unstable strain), a haze plant, Northern lights, trainwreck, and a good quality purple) Almost anything you home grow will knock you off your ass. Or you could go all out wild it's your call.
Personally though when picking strains I go from....one sativa dominate plant (90-100% sativa), one sativa dominate indica mix (60% or more sativa), then one indica dominate sativa mix (60% or more indica), and lastly I'd get a seed that was indica dominate (90-100% indica). That's how I always pick out seeds.