Everyone is correct, you can write and read on this subject for months, and it gets more confusing the more you read.
Some very simple advice from an old timer who has been using scopes since the very first HeathKit scope hit the market back in the 1950's!
I am still an experimenter, and like to buy, repair, and resell old high quality test gear, mostly HP.
The last time I changed scopes I decided that it would be my last scope purchase, (turned 79 a couple of days ago) so I did one heck of a lot of research to come up with what I thought would be my ideal scope.
In the end I settled on having two scopes. My primary scope turned out to be a TEK-2445B Analogue. In addition I wanted one that would display and store high speed digital signals as well. For that I settled on a TEK-2440.
Have been using them both for about 3 years and have yet to find something that I could not display.
If I was going to purchase just one today it would be the TEK-2445B. It is a real pleasure to use, and all the auto features blow me away. Makes it so easy to do waveform observation I wonder why I did not look for one sooner! It displays, numerically, frequency, amplitude, and just about any thing else you need to know about the waveform you are looking at.
You can purchase either one for a very good price on eBay, and there are a lot of very reputable sellers out there that will stand behind their sales.
Here is a link to my current test bench setup.
(The 2445B is on top of the 2440.)
http://www.mrrace.com/product_pages/other_items/MyTestBench/index.htmHope this helps,
George Race
Race Consulting