A type set is an example of each denomination for a particular coinage, so fractional farthing up to the gold £5 if you can afford it. By collecting in this manner you can see a range of coins which differ in both size and design. After a while you may decide that you like a particular denomination, but until you do it keeps all your options open. Personally, I find a date run boring as it comprises a number of similar coins which differ only in the date which may be too small to see easily, but there is no right or wrong and it is each to their own.
You can start with a single type set for a monarch, but this can be expanded to include type sets of the different coinages of that reign.
For example, George VI's initial coinage was in 500 silver and had the full titles on the obverse. Following India's independence the IND IMP was dropped on the 3rd coinage, so you have a different obverse design, though the portrait was unchanged. You have 3 distinct portrait types for Victoria, the Young head, Jubilee head and Veiled head. Elizabeth II has half a dozen portraits and she isn't finished yet!
The beauty of a type set is that it allows you to find the cheapest year for any denomination/type of coin. Go for a date run and you will end up with a gap for the key date that you feel reluctant to fill. Edward VII silver for example is relatively cheap for some years, but 1905 is way more expensive than the rest. If you got a 1902 set then you would have all the denominations issued during the reign at the cheapest price for any grade. 1902 is quite common in all denominations.
Aesthetically speaking, it is better to have coins with a similar grade and tone.