At a year old he will be feeling fairly settled in his current cage, but will also benefit from more space. So there are pros and cons to the Grosvenor XL and Savic Plaza in terms of familiarity. The Grosvenor is a similar height so will feel more familiar, be a bit safer, and means he won't be scared by extra space above him as he would in the Plaza. On the other hand the access is at the top and he's used to a front door. The Plaza will feel familiar in that it's the same depth as the current cage and a large front door for access as before - but it's a lot taller and he'll notice all the extra space above him and might find it a bit scary. It also has fall risks depending on how its set up. So set up makes a difference too.
So I would either get the Plaza but "reduce" the internal height by having 10" deep bedding. To do that you'll need cardboard or perspex about 5 to 6" high inside the bars, and fill it with 10" of bedding. That is a lot of bedding, but you don't need to clean out as often with more bedding so it lasts a long time.
This would be the closest to his current familiar set up - same front access, same depth of cage and same height above substrate level. But quite fiddly to set up maybe.
Or - get the Grosvenor XL, easier to set up and manage, have cardboard or perspex (or grass mats) inside the bars just at one end, and have a deep bedding end. This is easier, safe and a familiar height for him - but he will notice the front door isn't there any more. However he'll probably get used to it quite quickly but it's surprising how they notice changes.
Either way, if doing a cage move, post back on here before you do it so we can suggest a way to do it that helps him settile in quickly and avoids stress
