Good Morning, Niallman,

Unless space is a prime consideration, it's probably worth going directly to a 4 x 5 enlarger. Like lots of other darkroom equipment, they're selling for bargain prices on E-Bay right now, often very little more than for MF models. Since 4 x 5 enlargers are bulky, heavy, and a pain to ship, it's probably a good idea to look for one which you can pick up in person.

If you're thinking of MF now, LF may be just around the corner. A 4 x 5 model will probably meet all future needs; a MF may not.