[Sprint HTC One (M8)] ahecht:
I thought I would try to compile some of the useful tweaks for /system/build.prop and /system/customize/ACC/default.xml here. Feel free to respond with other tweaks. Change the line with a - to the line with a +.

/system/build.prop

***** Enable Tethering UI (thanks Captain_Throwback) *********************
-ro.wifi.hotspotUI=0
+ro.wifi.hotspotUI=1

-ro.bt.tetheringUI=0
+ro.bt.tetheringUI=1

-ro.usb.tetheringUI=0
+ro.usb.tetheringUI=1

***** Enable EPST ********************************************************
-ro.build.type=user
+ro.build.type=dev

***** Disable ADB Icon ***************************************************
+persist.adb.notify=0

/system/customize/ACC/default.xml

***** Disable NFC Icon in statusbar **************************************
-<item type="integer" name="nfc_show_icon">1</item>
+<item type="integer" name="nfc_show_icon">0</item>

***** Allow roaming by default (shouldn't be necessary) ******************
-<item type="boolean" name="allow_national_roaming">false</item>
+<item type="boolean" name="allow_national_roaming">true</item>

***** Disable "Set Timezone" notification ********************************
-<item type="boolean" name="disable_timezone_notification">false</item>
+<item type="boolean" name="disable_timezone_notification">true</item>

***** Set blinkfeed to not be the default home screen ********************
-<item type="boolean" name="default_blink_feed">true</item>
+<item type="boolean" name="default_blink_feed">false</item>

***** Disable Spark icon (DOESN'T WORK) **********************************
-<item type="boolean" name="data_icon_s4t_spark_enable">true</item>
+<item type="boolean" name="data_icon_s4t_spark_enable">false</item>

***** Tether Hack (requires installation of script from *****************
***** http://xdaforums.com/showthread.php?t=2712222 ***********
-<item type="boolean" name="tethering_guard_support">true</item>
+<item type="boolean" name="tethering_guard_support">false</item>

-<item type="integer" name="tethering_support_ipv6">0</item>
+<item type="integer" name="tethering_support_ipv6">1</item>

-<item type="boolean" name="use_default_profile_for_tethering">false</item>
+<item type="boolean" name="use_default_profile_for_tethering">true</item>

-<item type="integer" name="TetheringGuard_Rule">2</item>
+<item type="integer" name="TetheringGuard_Rule">0</item>

***** Enable horizontal quick-settings in status bar using the ***********
***** first five quick settings icons. These can be reordered ************
***** using the edit button on the regular quick settings screen *********
-<item type="boolean" name="support_minor_quicksettings">false</item>
+<item type="boolean" name="support_minor_quicksettings">true</item>

***** User AOSP-style recent apps ****************************************
-<item type="boolean" name="support_HtcStyleRecentApp">true</item>
+<item type="boolean" name="support_HtcStyleRecentApp">false</item>

-<item type="boolean" name="isHtcStyleRecentApp">true</item>
+<item type="boolean" name="isHtcStyleRecentApp">false</item>

***** Enable Harman/Kardon audio setting (requires H/K firmware from *****
***** http://xdaforums.com/showthread.php?t=2729173) **********
-<item type="boolean" name="support_harman">false</item>
+<item type="boolean" name="support_harman">true</item>

-<item type="boolean" name="support_boomsound_effect">true</item>
+<item type="boolean" name="support_boomsound_effect">false</item>

***** Enable Beats audio setting (may not have any effect) ***************
-<item type="boolean" name="support_beats_audio">false</item>
+<item type="boolean" name="support_beats_audio">true</item>

-<item type="boolean" name="support_boomsound_effect">true</item>
+<item type="boolean" name="support_boomsound_effect">false</item>

***** Enable Music Channel Setting ***************************************
-<item type="boolean" name="support_music_channel">false</item>
+<item type="boolean" name="support_music_channel">true</item>

***** Allow selection of download location in stock browser **************
-<item type="boolean" name="support_download_path">false</item>
-<item type="boolean" name="support_filemanager">false</item>
+<item type="boolean" name="support_download_path">true</item>
+<item type="boolean" name="support_filemanager">true</item>

***** Add Tethering quick-setting icons **********************************
***** to select by using the edit button on the QS screen ****************
***** (Add the lines with a + next to them, without the "+") *************
<item type="integer-array" name="quick_setting_available_items">
<int>0</int>
<int>1</int>
<int>2</int>
<int>3</int>
<int>4</int>
<int>5</int>
<int>6</int>
<int>7</int>
<int>8</int>
<int>9</int>
+ <int>10</int>
<int>11</int>
<int>12</int>
<int>13</int>
<int>14</int>
<int>15</int>
<int>18</int>
<int>19</int>
<int>20</int>
<int>22</int>
<int>24</int>
<int>25</int>
<int>26</int>
</item>
<item type="integer-array" name="quick_setting_items">
<int>0</int>
<int>1</int>
<int>2</int>
<int>3</int>
<int>4</int>
<int>5</int>
<int>6</int>
<int>7</int>
<int>8</int>
<int>9</int>
+ <int>10</int>
<int>22</int>
</item>

I've uploaded copies of the 1.54 build.prop and default.xml with all these changes below. Just remove .1.54.modified.txt, move them to the appropriate place on your phone, and do chmod 644 on build.prop (save a backup of the old files first!).