Dome-top = More space inside
Play-top = more space on the outside
With dome top and flat top cages, you can always create your own gym on the outside/top of the cage.
For a lot of space for a great price, you could always look into flight cages. I have one [ame="http://www.amazon.com/gp/product/B002UTZ040/ref=s9_simh_gw_p199_d0_i3?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=13C924VH55H3ZMFNGB0H&pf_rd_t=101&pf_rd_p=1389517282&pf_rd_i=507846"]HQ Flight Cage[/ame], 32 x 21 ([ame="http://www.amazon.com/gp/product/B004MZV1Q6/ref=s9_simh_gw_p199_d0_i5?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=13C924VH55H3ZMFNGB0H&pf_rd_t=101&pf_rd_p=1389517282&pf_rd_i=507846"]A&E version[/ame]) and one [ame="http://www.amazon.com/Double-Flight-Cage-Divider-Color/dp/B00494MWRM/ref=sr_1_2?s=pet-supplies&ie=UTF8&qid=1349371938&sr=1-2&keywords=double+flight+cage"]A&E Double Flight Cage[/ame], 64 x 21.
There is this flight cage, although I have no experience with it...
[ame="http://www.amazon.com/gp/product/B00176F5L0/ref=s9_simh_gw_p199_d0_i1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=13C924VH55H3ZMFNGB0H&pf_rd_t=101&pf_rd_p=1389517282&pf_rd_i=507846"]Amazon.com: Prevue Pet Products Wrought Iron Flight Cage with Stand F040 Black Bird Cage, 31-Inch by 20-1/2-Inch by 53-Inch: Pet Supplies[/ame]
I have a
WI32R for my mitred conure, and the
WI32 is the play top version.
I got my cages second hand (not necessarily used), so got them for good prices.
There are other options out there, but I would recommend staying clear of open top cages. If you do end up with an open top cage, then secure the top doors closed in some way that the bird could not open it from the inside. If you ever do open them, be sure there is a way to secure the doors open other than using a perch. I have heard of one too many deaths (and believe me, one is enough!) caused by an open top cage, and I wish to hear of no more!