The OpenWRT wiki[1] is a great resource for this. There you can find a Buyers' Guide[2], as well a Table of Hardware[3] with compatibility tables for vendors, models and OpenWRT versions.
I recently flashed a TP-Link TL-WR1043ND with OpenWRT and it worked like a charm. I'm planning to flash it with the Pantou[4] OpenWRT distribution so I can start running OpenFlow with real hardware.
I'm using WR943ND and have problems with WiFi - it usually works, but may suddenly lose connection and start not accepting some or all clients (usually looks as a failure to obtain address via DHCP). Requires me to power-cycle the router every now and then. Not sure whenever the problem is within the hostapd or kernel, and I'm too lazy and incompetent to debug it. It seems to work fine for others, so maybe it's just my particular hardware issue.
Also, about an year ago, switch support was nearly non-existent - they just had the configuration struct hardcoded right inside kernel and nobody (including me) hadn't enough patience to properly expose config to userspace. But that matters only if you want 802.1Q, which is rarely a requirement for typical home networks. And maybe someone bothered to hack that, already.
Otherwise TL-WR{7,8,9,10}4[13]ND is a good platform. Unless they changed something recently, I'm not aware of.
Not only that, but the WDR3600 has a significantly faster CPU, more memory and more flash than the WR1043ND. It's about 2 years newer too. Definitely worth a few extra dollars.
I'm a bit nervous about TP-Link, I have a couple of of small GigE switches and when they were at the end of a not that long cable (although maybe not the best quality connection) they couldn't sustain more than 100Mbit unlike a similar but slightly more expensive ZyXEL switch managed to support the 1Gbit mode.
I recently flashed a TP-Link TL-WR1043ND with OpenWRT and it worked like a charm. I'm planning to flash it with the Pantou[4] OpenWRT distribution so I can start running OpenFlow with real hardware.
[1]: http://wiki.openwrt.org/
[2]: http://wiki.openwrt.org/toh/buyerguide
[3]: http://wiki.openwrt.org/toh/start
[4]: http://archive.openflow.org/wk/index.php/Pantou_:_OpenFlow_1...