Premier Inns used to be my hotel of choice for work and leisure reasons for years. That changed over the last 2 years after their standards went down (food wise and service wise going downhill, no daily room cleaning, charging for early check in etc). I still use them occasionally if no other option available.
But the other main reason I don't use them in the last 2 years is their utterly extortionate prices in London - £250/£300 a night midweek sometimes which is laughable. When you can stay at Marriotts, Hiltons (and their various sub brands - Moxy, Courtyard, Doubletree etc) for FAR cheaper (£110-£140 a night) - and accumulate loyalty points, status, late checkouts, free breakfast, access to exec lounge with free drinks, access to onsite gyms ......why on earth would you book a Prem Inn as a regular traveller???
For those on a tight budget and /or who travel infrequently Travelodge are better these days, particularly in their refurbed hotels. Have stayed at several over the past two years with the one at Docklands Central being a highlight.