I don't think I have an ultimate must-have since there are too many I like! I DO love those pretty treadles/handcranks with the roses decals and the fiddle bases I think they're called...also like the hot pink Morse...
for the first person who wants the Pink Atlas - I'm sure you're meaning you're wanting a bargain but I've come across 2 pink Atlas machines - one is very pricey IMO but I think is in nice cosmetic shape - think the shop wants $175 as is (and says needs complete rewiring) or $300 serviced plus if they ship...the other is or was on etsy and I thought about getting it but decided I have other things to spend my money on- think it's $140 though plus shipping but for me it's driving distance - about an hour away. but the pic doesn't look as nice as the other pricier one. I'm near Houston and both machines are in this area (or were- I haven't tempted myself by checking to see if they're still available after a handcrank and fleetwood followed me home last time...