Elementalist and Mesmer viability PvE/sPvP?

[steve.2906]

I haven't played GW2 for over 2 years but wanted to return. I got bored of playing the same characters every time so I decided to start fresh with either an elementalist or mesmer. I got some experience with Mesmer but I'm afraid that it's not viable in CM fractals/raids/sPvP. Is Elementalist more viable, and if so, how difficult is it to learn compared to Mesmer?

By viable in PvE I mean the ease of getting accepted to parties and for sPvP whether you don't just get stomped because the class is underpowered.