Cold frame recommendations?

[kentvegplot]

I have been promised my choice of cold frame for my birthday this year.

I can't decide whether aluminium or wood would be better (aesthetics aside, that is). Also, is the polycarbonate OK, or should I really go for toughened glass ?

If it makes a difference, I intend it mainly for hardening off, also over-wintering hardwood cuttings and cold stratifying seeds.

All advice appreciated.

Thanks

[Two_Sheds]

If it's not to be pegged down, the heavier the better, ie glass and wood.

Wood will need to be treated every year, aluminium won't.

Glass breaks, polycarb doesn't (but it does pop out in a gale)