As I have a syrian then my personal opinion would be they (for first timers) would be the better one, they a practicaly tamed and when you get them into a routine then they are just the icing on the cake. Im still not allowed to hold trixie yet but going to try in a couple of days.
My sister has Roborovski's and you have to tame them an awful lot, they are really small and fast and can fight, best to watch and not hold, unless tamed well.
Sooty and Stripe were russians and one was tamed and one was abit grumpy! They fight quite alot and for you I would say the fighting might be a bit much as a first timer.
My friend(Sky Orchard)also known as lunar wing, has Chinese she got them off a family friend and even though they are resonobly tamed then like other dwarfs they fight. However, they dont require to be tamed as much, but would still need it.
My opinion in order:
1. Syrian- Fantastic first time hamster, comes pretty much tamed
2. Chinese- Still need taming but not as small as the other two dwarfs, probably about 1 makes half a syrian
3. Russian- Fight is quite a bit of a problem, once tamed well cuddly pets
4. Roborvski- Best as watching hamsters, rather then holding, a bit more fiddly to hold. 2 make half a syrian
If you live in England then i would suggest that you use Pets at Home:
http://www.petsathome.com/ then hover over small animals and right near the bottom then small pets available in store and click on any of the hamsters. Even though this is a pet shop, they are the best place for advice, this doesnt necersarily mean you have to get them from here!