As this is an extremely important tool in your diagnostic arsnal I would take as much time as possible to research what makes a good scope (bandwidth, record length etc) this is a bit much to take in at first but pays dividends as you wont end up (as I have) buying multiple scopes.Some great information can be found on IATN on this subject, and 1 post in particular goes into great detail about scope specs, if I can find this I will post here.
I have been in your position and it can be very confusing. It is easy to buy something that appears to do the job only to find its not as great as you first envisaged.
My first purchase was a Fluke 98 and although not a BAD machine it is aimed at the beginner and its pre set menu's soon become a hinderance rather than a help. Also its bandwidth can be limited for faster signals (ac excited phase sensors).
My next purchase was a Fluke 199c which has been a great perfromer and a massive improvement on the Fluke 98, its only short coming in my opinion is that it does tend to pick up interferance from ignition which is often displayed on other waveforms.
I have recenlty purchased a Tektronix bench scope which does away with this interference and is the ideal machine for me, but its down side is it is not a portable model as it requires 240v.
I looked at the specification of the Pico and in my opinion it seemed to lack the bandwidth and record length that is required to be reasonably future proof scope.
One thing that seems to be blatantly obvious, dont go for a scope that is labled automotive, you will get a better spec for less money in the electronics field.
I can recommend a Frank Massey scope course, this course helped to lift my diagnostic technique and at no time did Frank try to sell me a scope. It probably wouldnt be a bad idea to take the course before you purchase a scope, although if you could get a brief idea of what a scope does and what basic waveforms look like tis would be a help.
Dont forget that the leads that you use are also important as cheap ones can limit bandwidth, no point in having a 100MHZ scope with 10MHZ leads.
As with everthing else in life you get exactly what you pay for, I have spent some time looking for the Holy grail of the automotive scope world and ended up spending £7000 to get what I think I needed, there dont seem to be any short cuts. Pay as much as you can afford in the electronics field and hopefully you will be future proof as possible.
Have a look an www.telfordelectronics.co.uk , this is where i purchased my Fluke 199c from. These are ex-demo units at reduced prices, and if you dont get on with what you buy hopefully you wont lose any money if you were to sell on.