tool should first take into account just how agile you want to go, and if you want to go all the way into one of the agile practices make sure to look for specific agile terminology for ALM vendors you research. Words like sprint planning, iteration, user story, story board and other terms specific for the type of agile workflow you want to adopt.
An outlook: expect solutions to get better at agile
There were many people in my industry who wondered if Agile was going to be something like the Atkins diet. That is to say it would get very popular very fast, and then people would get bored of it and move onto something else, like the South Beach Diet. Agile is very likely to be here to stay, it has seen a lot of success and is still growing. One complication of agile adoption, especially on enterprise scales, will be discerning the truly agile ALM tools from the legacy rebranded ones.
One thing is for certain. Makers of ALM tools, developer tools in general, are paying attention to the trends. A study recently done by Forrester on ALM developer tools that showed 35% of the respondents claimed to be using an Agile workflow, just 13% using waterfall. Just 'how' agile is everyone, pretty agile it turns out. As a result ALM tool makers will continue to provide more and more agile specific capabilities and in turn will make it easier for development teams to adopt agile practices. Expect like minded firms to develop strategic partnerships provide more well rounded ALM solutions that share a common agile vision. As a result, agile teams can find tools geared specifically to their needs that provide better alternatives than current legacy solutions.