There's really no "space marine" army, per se, and each army has a mix of traits and styles that are heavily dependent on caster. Honestly, any army can do a small, more elite list if it wants, though if you go for more Jacks and fewer infantry, you'll probably get what you want.
Khador - Soviet style. While a lot of people see their nice chunky jacks and think they must be the center of the army, they are actually generally the faction who takes the fewest jacks, usually only taking one or maybe two outside of a couple of casters who can run more. They actually really love their infantry, and many specialized infantry units generally make the bulk of their armies. While you can get more elite heavy infantry, Khador has a real love for a few units of it's lighter infantry, so it's probably not the best choice, unless you plan to relegate yourself to just a few casters who like Jack-heavy lists. They can shoot, they can be elite, but they generally like quite a bit of infantry in many lists, so maybe not.
Protectorate of Menoth - Religious zealots, much in the vein of the religious fanatics of the Imperium (but with devotion to Menoth rather than the Emperor). These guys actually are the best Jack faction in the game currently, with lots of Jack support, but their infantry is pretty damn good too. Their other big game-play theme is Denial, with many abilities that can mess with opponents game plans. You'll generally want at least one unit of infantry to be blockers, as our jacks are a bit slow and better at counter-punching, but they can actually go quite jack heavy on most lists, which makes them a good candidate for you. The only thing is that outside our Jacks, our infantry doesn't do shooty very well(but some of our jacks can do shooty VERY well, especially with the right support). I'd definitely list it as a possible for you.
Cygnar - the "good" guys (well, comparitively good, they've still got a lot of skeletons in their closest), and fluff wise the richest and most technologically advanced, they are the best ranged faction in the game. I'd compare them to Tau, except they don't suck in Melee, and they do the Combined Arms thing pretty well. While they don't have heavy infantry, they do have a few worthy jack marshals, and a few casters who love jacks, which can keep your force small and "elite". Definitely a possible.
Cryx - These guys are tricky and love debuffs. They're often a bit of a glass cannon, with lots of damage potential, but if you can get around their tricks, they're boned (being the undead, often quite literally). They love infantry, often lots of infantry or infantry that comes back to life or model that can create more infantry. They're pretty poor at shooting for the most part, so I wouldn't recommend them for combined armies. Probably not what you're looking for.
Hordes armies -
Legion of Everblight - they love beasts, and you can easily have lists with just beasts and a few solos, which makes it very small and elite. They can do shooting quite well in a few lists, though they love melee as well. It might be worth looking into.
Trollbloods - They like infantry more than any other Hordes faction, they're tough and hardy, generally hard. Their shooting isn't generally the best, but there's a few lists that really bring it to the fore, and they have a few units of heavy infantry/cavalry that really help keep the model count down. They are a bit Ork like, except that they don't tend to swarm - think of them as an ork army that's made up of just the elite stuff and nobs rather than a green tide. Combined arms and they can be made pretty elite, so a maybe for you.
Skorne - generally doesn't do much shooting, so probably not what you're looking for.
Circle Oboros - is a more tricksy glass cannon faction, with lots of movement shenanigans. They do some shooting (well, spell slinging), but probably not as much as other factions.
Hope that helps narrow down things a bit. I can give a bit more concise info on any of the factions if you're interested in them.
It's all in the name.
Looking for a club in Brisbane, Australia
? Come and enjoy a game and a beer at our friendly club in a pub, Sunday nights from 6:30. All brisbanites welcome, don't wait, check out our Club Page on Facebook
for details or to organize a game. We play all sorts of board and war games, so hit us up if you're interested.
Update:From the 25th of May 2014 we'll be Meeting at The Junction pub in Annerley, opposite Ace Comics and Games
Still playing 40k, Warmachine and board games of all sorts!