Terrain: (choose and place) or (place and choose)

Hi there.
I think that terrain selection works in a slightly more draconian way than either of your options.
The way I have played it is
1 to select the terrain in accordance with the menu of terrain choices. Compulsory piece or pieces and then 2-3 optional pieces
2 Pile up the selected terrain with any waterway first, then your compulsory pieces and then the optional pieces.
3 dice for each piece in pile order.
This means that if one quarter of the board is filling up with terrain you cannot then ferret through your terrain box for a suitably shaped piece that you can just squeeze in.
It also means that it pays to give careful thought before the game to what sort of board you are trying to achieve to benefit your particular army. It might also pay to artistically design your terrain pieces so that you can get the maximum number onto the board if that is your aim.
And good luck. It is surprising how many 6's are throwable during terrain selection.

This how I do it

I too agree with Gonatas:-

1) Start by selecting ALL your terrain (including it’s desired size and shape).
2) Place the Waterway first, then the compulsories, lastly the optionals (in any order).
3) As each individual feature is picked up, dice for its location (discarding if it won’t fit).

I find it best to place the largest features first, but leaving space for the smaller ones.

Mind you, I don’t usually mix the terrain sizes…I have them either all large or all small.
After all, if I want an open battlefield, and select the minimum of terrain, why would
I want a large piece?

Likewise, if I want a camped crowded battlefield, why would I select small features?
A single large feature, say 6 x 3 BW in size, still covers more ground than two small
ones, even if some of the large features get discarded (in other words, it’s the amount
of ground covered, not the final number of terrain pieces, that is important).

One little trick you can try with Arable terrain is to select as many large pieces of Plough
as you can (two compulsory and one extra), and place them so they deliberately prevent
any other terrain from fitting in that quarter. When it comes time to dice for the last feature
(which must be Rough or Bad Going), with luck there won’t be anywhere to place it, leaving
you with a nice flat open battlefield with no hindering terrain.

I cannot find in the rules a requirement to put the terrain in order of placement, within categories. You must, however, pick all the potential pieces prior to placement rolling.

There are three categories. It seems to me that you just pick all the terrain you want to use and then roll for placement within categories.

Waterway must go first. No choice here.

Next comes compulsory. If one then roll for it. It two, then pick one as you want, and roll for it, then pick the other one. If different sizes, for example, no need to determine the order in advance.

Optional. if, two, pick one and roll for it. Then roll for other one. Likewise, if 3. Pick any one of the 3 and roll for it. Then pick either of the next 2 and roll for it. Then roll for last.

So, for example if you have an optional Woods, Gentle Hill, and Scrub, you and pick any of them for first selection. Then pick the second one based on the placement of the first one. Then roll for last one.