I have a 30" tall 150g (like a 125g but 6" taller) and I love it.
yes, reaching the bottom is a pain in the butt - but thats why they invented step ladders and reach assists. remember, you spend all week looking at your tank but only about an hour or so a week doing the actual maintainence. its totally worth it.
the extra height combined with the 6 foot length looks amazing.
with out question, get the 210g. lots more water, much nicer looking tank.
doesn't take up any more space. cost is almost the same other than a bit more for the tank itself.
its a no brainer IMO
but really either tank is obviously nice. but I think you will be happier with the extra viewing area and water volume/swimming room of the 210g