Switches are like so many other things in life - you get what you pay for.
Sometimes you can pay less and get enough (i.e. it works well enough)
Sometimes you can pay less and not know what you're missing (you don't know what some of those advanced features are anyway, even though they could be useful)
Sometimes you pay more and get features you don't need/want/understand
Sometimes you find just the right option.
Start off by determining the importance to your business. If the switch blows out and all your servers go dark, how much will that cost you if it takes an hour to get it back up? 4 hours? a minute?
Look also at how much traffic you're pushing through your network. If you just need ports but aren't pushing many packets then a cheaper switch may suffice, but if you need every port to run at full line rate with no packet drops then you need something bigger.
Do you need the switch to just pass traffic, or do you want statistics (e.g. SNMP, RMON, etc.) so you can track which ports are busiest?
Then, of course, there's a budget. It could be $100. It could be $10,000. Your options are limited at $100, but $10K will cover a lot of options.
While you're doing this, consider expansion room. Are you likely to need more ports soon? Are 48 ports enough? Maybe a chassis-based switch that's expandable would be a better option.
At the high end you might consider anything from Cisco. Their
Catalyst range of switches are the workhorses of many networks. They also come with a matching price tag.
Other options worth considering at the higher end would be Force 10's. Force 10 is known for their 10-gigabit network equipment, but their
S Series switches are a powerful play.
Then there's
Juniper's EX range. Juniper are known more for their routing platform (I guarantee most of your internet traffic goes through a Juniper router at some point), but their switches are a natural progression.
Coming down the line a little, look at Brocade's
FastIron switches. Formerly Foundry Networks (before they got bought out), I" ve used (and continue to use) their switches in my network. If all those are above your price bracket then
HP ProCurve switches are worth a look.
All of the above still may do more than you need, though. If all you really, really want is link aggregation and don't care about the rest then I'd probably go for a
NetGear over the other lower-end players such as D-Link or LinkSys (even though LinkSys is now owned by Cisco).