Asking people which 3D program to use is kind of like asking people their favorite ice cream flavor. 
Just because someone else prefers one product over another doesn’t mean you will also. The artists on my team all use Maya, but I’m a Blender user myself. My original reason for choosing Blender (back in the 2.4x days) was simply that I couldn’t afford a commercial 3D package, or at least I couldn’t justify the expenditure. Now, I stick with Blender not because it’s free, but because it’s gotten to be very good and I’m accustomed the its quirks and way of doing thing.
But, there are some pain points with Blender and UE4. Every release, they get to be a little less painful, but they are there. One of the biggies revolves around the FBX license. It’s not compatible with Blender’s GPL license, so Blender is unable to use the official FBX SDK. That means the FBX import and export from Blender are imperfect and usually at least a few versions behind in terms of supported features. The Blender exporter is quite decent now. I’ve only had one significant problem with the 2.70/2.71 builds and UE4, which is that Blender seems to insert an additional root node into armatures. This doesn’t affect anything if I’m exporting both the animations and the model/armature, but it does make it a pain to try and match an existing armature like the ones used in the UE4 templates and sample code. That extra root bone keeps the skeletons from matching. Blender’s FBX importer is not quite as robust as its exporter. It, too, has gotten much better in recent releases, but it still doesn’t support importing armatures or animations, so you can’t round-trip from UE4->Blender->UE4 unless you use another intermediate program in between.
Personally, I’ve yet to encounter something I need to do that I haven’t been able to do in Blender, but there have been things that I’ve had to spend time figuring out. Let me also qualify with a couple things. First, I’m a programmer who occasionally pretends to be an artist, not a full-time professional game artist. Second, our team only switched to UE4 (from Unity) a little over a month ago, so we’re far from established experts on this.
On the other hand, Maya, being heavily used in the AAA games industry, is essentially (if not officially) the reference 3D program for UE4. Because of that, you’re not going to experience as much in the way of headaches trying to get content over to UE4. With the A.R.T., it’s relatively quick and easy to rig a character for use in UE4. Most of the official and unofficial UE and UDK tutorial you’ll find are likely to use Maya, and there’s no doubt it’s a heavyweight of a program that can do amazing things (when it’s not busy crashing, at least).
Whether Maya’s benefits are enough to justify its cost is a purely subjective call. I’m at a point where I can afford and can even justify the expense of Maya if I want to, but I find I can work so fast in Blender with their “one hand on the keyboard, one hand on the mouse” philosophy and their extensive, context-sensitive key bindings, that I’ve always gone back to Blender after a few weeks whenever I’ve tried to switch to Maya or another package. On the other hand, I know a great number of people who feel they are far more efficient and productive in Maya (or 3DS Max or Modo or [insert favorite 3D package here]) than Blender or [insert disliked 3D packages here]). A huge factor is simply going to be your personal tastes and preferred mode of working.
If money is a pressing concern, there’s no reason *not *to use Blender. There will be some minor headaches along the way, but nothing you can’t work around. If money’s not an issue, then I suggest you download the Maya trial and give both a try. Work through a few tutorials, and see which one feels more natural to you.
In both cases, there will be a learning curve and frustrations, but you’ll get over the hump after using it for a bit and really start enjoying it regardless of which one you end up choosing.