reloop IQ2+ :D more for you money :D if you realy want one of the 2 DJM's it depends on you previliges if you want it for the effects i say take the 400 if you want to record directly i say take the 350
I'd definitely choose the DJM 400 over the 350, because of the sampler/roll function on the 400, as well as the fact that it has more effects and you can control them in a better way. the 350 only has 4 effects that you can only use on the master out. the 350 nor 400 have XLR outputs, so be aware of that if you use monitors or PA amps.? There are however many alternatives that offer not only better quality, but also a better price. The Ecler Nuo 2.0 is a good example, it has an extremely high build quality, it lacks effects though. but because of the price ( 380, compared to the DJM 400 which costs 550) a seperate effects unit can be bought. So I'd go for something else, but if you still want a DJM 400 or 350 (which I understand, they're great fun) go for the 400.
When you've got 300, why should you upgrade to one of these? They are all 2-channel mixers and they are all quite similiar to eachotter. So I think you'll need to look at a different mixer, like the Reloop iQ2 or A&H Xone:22.
my budget is limited thats why i prefer 2 channel mixer and i don't need 4ch. Why DJM?, because i trust to Pioneer. And mixing on djm300 i'm get bored without effects. Thats why i want new mixer with effects