Ugh ema just to let you know... Getting the single CN here to BC will cost you 237$. To get it to Vancouver that's what it cost. I forgot what site but if your ordering one and can't find it cheaper I'll find what site it was.
I clicked CN because it's my favorite but I also have a Petco rat manor that got for free with a rescue. I HATE it. and a marchioro Tommy cage (not listed) for my single geri girl I got it used on craigs list and I LOVE it. I had a SP habitat defined for rats a few weeks ago but I hated it so much I gave it away to someone who promised not to use it for rats haha
Oh and I also have some kind of huge SP cage that my mom found in the trash a few weeks ago. I'm not sure what kind it is because I didn't buy it. I'm going to clean it up and use it for a hospital cage. It's in great condition and had a whole bunch of unused things inside of it like a bag of food and a bag of bedding and a brand new igloo, wood chews, and toys. It's awesome that my mom just found it! I sanitized all the toys and froze the bedding and wood chews but threw out the food because it wasn't any good.
I voted martins 699 (can't believe I'm the only one with one) but I use my double CN for my fosters. I like the martins 699 better, but the CN is my second favorite. I technically have a bunch of other smaller cages that i've been gradually giving away and selling.
I have a homemade cage built out of a closet (80x50x160 cm) that is suiteable for up to 4 rats .. I sometimes take care of rats whose owner go on holidays and they live in there.
My rats live i a cage especially built for rats by a German company. It is called Unidom and made out of steel. Newer ones are made out of aluminium. Its about 90x56x180 cm and suitable for 6 rats - and I keep 6 in there I love my Unidom =)