It all depends on what you want to do. In my personal opinion ele's are VERY overated. Rangers used to be but are shuned more which means you can play with builds more rather than picking up a random build.
I personally think MES is a fun profession just because imo it's the hardest caster class but can do anything caster oriented (even though you can equip daggers, do 0 dmg from them, yet they foe takes aprox 35 dmg each time you attack from a skill).
Also MES can imulate the same as any other class (pref caster) and can cast at OVER 12 cost and use the other professions elite. As for synergy with heroes, depends on how you want to use heroes. I've never had an issue with running any heroes even though people normally perfer a specific set. I norm run 3 necro heroes, but also have run 2 mes 1 n/rt, 3 ele, 2 mo 1 war, ect. You find what works well with what in each situation.
If you want to have fun tho and create your own play style go mes honestly. It's probably the least played profession and people will probably call you a noob or what not, ppl dont play mes, mes suck, blah blah blah. It's just the hardest to learn and find a play style.
You should try to experiment with professions though to find which you like the best. People hate on alot just because they can't play them requiring to much skill ect. Yet they love the professions everyone else runs because they can farm all these areas, solo this, do that and all run the same builds.
Paragon is VERY useful yet not used properly in most cases. They are the ONLY buffers in the game but can buff/attack if you want depending on what you do. Monks used to be only heal and prot with a few that ran a hybrid build who were "noobs" then. But now hybrids aren't uncommon and only the more skilled players will run them effectivly.
Check out
www.guildwiki.com or gw.gamewikis.org and just read up on the professions primary atts and look at the skills and base your primary off that. They all have perks and severe downfalls. Yet alot are still overhyped and overplayed (some ever overpowered) in my personal opinion. But you'll find everyone only wants to URSAN most everything which is lame and overpowered. Yet PVP guys complain that skills are overpowered just because they're build can't beat it and they're scared of change (and so they can overpower that same build so it's a never ending circle).