I think everyone agrees to say that she's best as Tanky Mpen, relying on her base damage. Basically what you do is build magic penetration in lane for ridiculous lane dominance, and you transition to tank items such as Sunfire Warmogs, Frozen Heart, Randuins, whatever floats your boat.
If I see them stacking health I'll pick up a Rylai's and upgrade my haunting guise into a Liandry's. Hell, throw a Q on the tank as kite and W their entire team is tons of damage from Liandrys. But I never, ever get it in lane of before they stack health because everyone does anyway at the moment. Also, Rylai's is very good for the spider form, hitting Q and being able to get a lot of skittering frenzied hits is TREMENDOUS damage.
Anyway to answer the OP's question, there is hardly any matchup where you're gonna lose the lane as Elise, the thing is there are champions that if you go even with them, you're just losing because they'll outscale you tremendously in late game. So what you need to do is basically buy TONS of wards, and act as a huge lane bully to make sure you're actually getting a significant lead. Make sure you give them nothing, absolutely nothing, they shouldn't even be allowed to go in XP range for some champions, such as Jax etc.
Then when significant objectives are in view, you can leave the lane and roam, usually after you completed HG and Sorcs, you deal true damage to the AD carry, the support and the Mid, so feel free to roam a little bit because you're Elise and you chase like a boss and they won't understand what hit them if you can land one rotation on their face. Easy to rack up kills or assists there.
In teamfights, I find myself mostly going all-in on the AD carry or the AP carry and using my spider E as a "don't focus me card". If you've had the laning phase you're supposed to have you'll always be pretty strong when first teamfights kick off, make sure you let the enemy squishies know about it.