We originally were big fans of Weller irons and used them in school but when it came time to stock the Adafruit lab we decided to go with a Metcal MX-500 on the recommendation of a friend. It was a good recommendation! Metcals are really heavy, durable and heat up ultra fast.
They're easy to switch tips, and can power two different soldering stations (we use a hot tweezer on the 'alternate' station). The wand is light and easy to grip.
The only weird thing to watch for is that the temperature is set by the tip, not the station. The station only has an on-off switch. This can be good when you're using only one type of solder, say leadfree (700 degree F tips) or lead (600 degree F tips) but can be annoying if you use both - although we suppose you can just go with the hottest tips.
Metcals are a little pricey but you can pick one up used on ebay for around $200 (thats what we did).
The nicest thing about the metcal is the wide assortment of tips available. They're a snap to swap - takes only a few second of pulling the old tip out and pushing in a new one.
For general thru-hole we like the screwdriver tip STTC-137P (shown on the wand)
For soldering FPCs or reworking a long row of pins, the SMTC-061 (all the way on the right) is very handy
For fine pitch rework we use the STTC-122 (second from the right)
We also like the two long 'hard to reach areas' tips STTC-107 and STTC-140. Great for getting underneath microSD holders and miniUSB connectors.
We also got a hoof tip SMTC-1147 (second from the left) but haven't used it yet since we don't do drag soldering so much.