With regards to the aforementioned take-over rumours, what about Spain's Vueling? The two carriers have comparable fleet types, a similar focus on main airports and a take-over would give EZY a larger share of the Spanish market, including a large base at Barcelona.
Wizzair seems to have more of an 'ultra low cost' business model, similar to that of Ryanair. I feel this is something EZY are trying to differentiate themselves from.