Depends on what you're after. The effect of oral mephedrone can be easily acquired by a combination of for example 4-fa & Methylone. I think there is no other RC that comes somewhere close to the effect from nasal administration.
In my experience, oral administration yields a longer AND more intense high - I was never able to get anywhere near oral effects with nasal administration, no matter what the dose (and since snorting it is painful as fuck I quickly abandoned it completely). I also found that oral administration produced the same kind of rush, just with a delayed onset - as soon as the mephedrone starts to work, there is a definite 'rushing' sensation, much stronger than the onset of MDMA for instance. It also plateaus off more smoothly, while I remember insufflated doses ending with something of a crash.
Naaaah, well, it is similar in sense that it does all the effects but intensity is not even remotely close, weak euphoria and I tried various doses, best was ~300-350mg which still wasn't very euphoric, 400 and more mg is plain unpleasant.
I'd say Morpheus19's suggestion is best, combo of 4-fa and methylone should be VERY euphoric from what I heard and quite close to 4-MMC. Both these RCs are very nice.
It's similar to comparing 3-FA with 4-FA, 3-FA sucks with little euphoria but is more stimulating.